In general this invention relates to a laser powered surgical instrument and more particularly to one that provides an efficient and safe means for delivering laser energy to tissue for the purpose of operating on the tissue.
The operating instrument of this invention will be described in connection with an embodiment adapted to be used in eye surgery and particularly for cataract removal. However, the invention can be embodied in devices which are adapted to other surgical purposes.
The use of laser energy to perform eye surgery is well known. There are a large number of known devices and patents which are relevant to this art.
One recent patent is the Eichenbaum U.S. Pat. No. 4,698,828 which contains an adequate description of the background in this art and contains a reference to a number of relevant patents. In addition, a useful text that describes both principles and applications of laser surgery in Ophthalmology is the text The Nd-YAG Laser In Ophthalmology by Roger F. Steinert and Carmen A. Puliafito, published by W. B. Saunders Company in 1985; ISBN O-7216-1320-9.
The desired parameters for a laser operated surgical device are the requirement of efficiency and small size coupled with avoiding damage to adjacent areas of the tissue being operated on. Enhanced safety for the operator as well as safety for the patient by minimizing exposure to laser light are goals of any design for such an instrument. The small size provides the advantage of making it possible to operate through a very small incision; a three millimeter incision being a goal in cataract surgery. Efficiency of operation serves the advantages of (a) keeping down the overall weight, cost and size of the instrument (b) minimizing the amount of heat or other energy transmitted to adjacent tissue and (c) assuring maximum effect on the tissue to be severed.
Accordingly, the major purpose of this invention is to provide a surgical instrument meeting the above requirements. A related purpose is to provide such an instrument that generates a minimum of heat and has the least possible impact on tissue other than the tissue to be operated on.
Trauma to the patient is reduced by providing minimum size incisions and delivering the minimum amount of energy to the patient consistent with performing the operation involved. Trauma is minimized by developing as little heat as possible and avoiding loss or scattering of radiant energy into the patient's tissue other than at the desired site of the operation. Thus, safety, comfort and minimum trauma consistent with performing the operation is a goal of any such surgical instrument.
More particularly, from the point of view of minimizing trauma, enhancing safety and minimizing size of surgical instrument, it is important to provide as efficient an operating instrument as possible. The efficiency desired is one in which the maximum percentage of input energy is delivered to the tissue to be fractured or emulsified. Manifestly, the greater the percentage of input energy that is delivered to the tissue to be operated on, the less energy will be delivered to other tissue and, in general, the smaller the operating instrument can be. Thus a goal of this invention is to provide a surgical instrument in which a high fraction of energy is delivered to the tissue to be operated on.